Tube expander

ABSTRACT

A segmented tube expander with overhung expander segments which run on rectangular glide surfaces or carriers on a truncated pyramid; the segments are scored against lifting off the glide surfaces and are constructed to prevent contamination of a lubricant between blide surfaces and segments.

United States Patent [191 Wimmer et a1.

TUBE EXPAN DER Inventors: Helmut Wimmer, Mulheim/Ruhr;

Wilhelm Feldmann, Duisburg; Wilhelm Schauenburg; Reiner Heimerzheim, both of Mulheim/Ruhr, all of Germany Mannesmannrohren-Werke Aktiengesellschaft, Dusseldorf, Germany Filed: Sept. 5, 1972 Appl. No.: 286,185

Assignee:

Foreign Application Priority Data Sept. 6, 1971 Germany 2145069 US. Cl. .L 72/393 Int. Cl B2ld 41/02 Field of Search 72/393 Mar. 26, 1974 References Cited UNITED STATES PATENTS 3,583,200 6/1971 Cvijanovic et a1. 72/393 2,943,667 7/1960 Ewing et a1. 72/393 808.030 12/1905 Faessler 72/393 601,689 4/1898 Wallis 72/393 .Primary Eicaminen-Lowell A. Larson Attorney, Agent, or FirmSmyth, Rostin & 'Pavitt [57] ABSTRACT A segmented tube expander with overhung expander segments which run on rectangular glide surfaces or carriers ona truncated pyramid; the segments are scored against lifting off the glide surfaces and are constructed to prevent contamination of a'lubricant between blide surfaces and segments.

2 Claims, 3 Drawing Figures PA'IENIEMARZS m4 SHEET 2 U? 3 Fig. Z

TUBE EXPANDER BACKGROUND OF TI-IEINVENTION The present invention relates to a tool for mechanically expanding steel pipes. The purpose of the expansion is to calibrate and to gauge the cross-section of the pipes or tubes and to strengthen the material by means of cold working, as resultingfrom the expansion. Mechanical tube expanding tools usually employ a conical, poly-corner bar carrying segments which engage the inner wall of the tube or pipe to be expanded. Surface portions of the segments opposite the ones engaging the tube, bear against glide faces-on the conical bar. As the bar is shifted axially, relative to the segments, the latter are spread and expand the tube or pipe in which this tool has been inserted.

The operating, mutually engaging cam surfaces of the bar and segment undergo high surface pressure and this requires very reliable lubrication. Additionally, quite frequently scale breaks off the inner surface of the tube when expanded, falls between the segments and adheres to the lubricant at the edges of the glide surfaces. The scale mixes with the lubricant during the next displacement of the segments and is pulled in between these glide surfaces and damages them.

DESCRIPTION OF THE INVENTION It is an object of the present invention to provide for a construction of a tube expander head so that reliable lubrication of the respective gliding surfaces can be maintained and the lubricant will not be contaminated. Thus, it is an object of the present invention to improve segmented tube expanders of the type referred to above, so that its glide surfaces are no longer endangered by damage by such contamination.

The tube expander in accordance with the preferred embodiment of the present invention is comprised of a poly cornered body, e.g., a truncated, polyhedral pyramid, having projecting carriers of rectangular face. Expander segments ride on the carrier elements, engage the respective faces and extend down into the grooves along side of the'carriers. Holders are provided, preferably at the front and rear ends of the segments gripping around the carrier, and extend into undercut grooves so as to prevent lifting of the segments from the carriers.

The operating glide surfaces on the carriers are thus completely covered by the segments. As they are rectangularly shaped, they will not be contaminated by scale which may mix with the lubricant. The rectangular contour of the glide surfaces is particularly advantageous for lubrication. The glide surfaces together take up the pressure force when a tube is expanded. The rectangular (rather than trapezoidal) contour of these surfaces do not offer maximum surface area for taking up the expansion pressure, but the increase in surface pressure per unit area is slight while the reliability is considerably increased, as compared with prior art expanders which tended to maximize available support surface for the expander elements and disregarded the lubrication problem.

DESCRIPTION OF THE DRAWINGS While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention, the objects and features of the invention and further objects, features and advantages thereof will be better understood from the following description taken in connection with the accompanying drawings in which:

FIG. 1 is a section through an expanderhead in accordance with the preferred embodiment of the invention; i

FIG. 2 shows a portion of a front view of the expander head shown in FIG. 1; and

FIG. 3 is a side elevation of the expander head.

Proceeding now to the detailed description of thedrawings, an expander head is comprised of a truncated polyhedral pyramid 1, for example, a pyramid with a dodecagon as base. This head may be mounted on a support rod (not shown) by means of. which the head is pushed into andthrough a pipe or tube to be expanded. The generated (geometrically) surface 3 of the pyramid (altogether twelve as arranged around an axis) are glide surfaces. Grooves ll are'cut into body 1 and in between the individual surfaces 3. The grooves taper in axial direction towards the apex of the pyramid, so that the remaining portions of .pyramid surfaces 3 are actually rectangular. These rectangular glide surfaces 3 are tilted relative to each other due to the polyhedral configuration of body 1 and they are incluned to the axis of the pyramid. The grooves 11 are actually cut where the corners of the pyramid would be.

Segments S ride on glide surfaces 3 and in immediate abutment therewith and by operation of glide faces 9. The outer surface 7 of each segment 15 matches the inner contour of a pipe to be expanded. Thus, this outer surface is curved andextends axially (not conically). The segments 5 can glide by means of their respective surfaces or faces 9 on the glide surfaces 3 of the body 2 thereby changing the effective diameter of the outer surface.

The segments can be constructed from plural parts with a glider having glide face 9 running directly on the glide surface tracks 3, and -an armoring covers the glider partially and defining the operating expander surface 7. Grooves 11 have undercut portions 19 so i that carriers 13 worked out of the base 1, have T- shaped construction. The segments 5 have sides '15 which extend laterally down into grooves 11 and along the sides of the respective carrier 13. The segments 5 are additionally provided with holders 21 and 23, bolted to the axial end faces of segments 5. These holders have noses which project into the undercut grooves .19 to prevent the segments from lifting off; they have to be axially slid onto the carriers 13.

Upon operation, the tool is inserted as a whole into a pipe or tube to be expanded; whereby, the segments have position close to the apex end of the pyramid. Next these segments. are pushed towards the base end of the pyramid 5 so as to expand a portion ofthe tube. The segments are then retracted towards the apex, and the body 1 is moved further into the tube whereupon the segments are again shifted into tube expanding position, etc. This way, the tube or pipe is stepwise expanded. The segments may be moved, e.g. through hydraulic means, or could be pushed manually, e.g. 'by means of a hammer or the like into expanding position, while being loosened from the other end of the tube.

The invention is not limited to the'embodiments described above but all changes and modifications towards the axis due to the pyramid configuration,

the grooves between the carriers having undercut configuration so that a cross section through each carrier has T-shaped contour;

the segments each constructed to have an uninterrupted, rectangular glide surface for gliding on the rectangular glide surface of the respective carrier in surface-to-surface contact therewith over the entire rectangular surface of the segment for load bearing contact with entire portion of the carrier surface underneath and with lubrication in between, the segments having sides respectively extending from the glide surface of the respective segment along-side the respective carrier and into the respective adjacent tapering grooves; and

holding means on each of the segments and gripping around the respective carrier for projecting into the undercut portion of ther-espective two adjacent grooves thereby holding the respective segment on the carrier.

2. Expander asin claim I, the holding means provided on axial end faces of the segments. 

1. Mechanical expander for pipes or tubes having a support body and expander segments, the improvement comprising: the body being constructed in polyhedral pyramid configuration, having grooves tapering towards the apex of the pyramid configuration so as to define carriers projecting from the body, the carriers each having an uninterrupted rectangular glide surface, said tWo faces being tilted relative to each other due to the polyhedral configuration, and inclined towards the axis due to the pyramid configuration, the grooves between the carriers having undercut configuration so that a cross section through each carrier has T-shaped contour; the segments each constructed to have an uninterrupted, rectangular glide surface for gliding on the rectangular glide surface of the respective carrier in surface-to-surface contact therewith over the entire rectangular surface of the segment for load bearing contact with entire portion of the carrier surface underneath and with lubrication in between, the segments having sides respectively extending from the glide surface of the respective segment along-side the respective carrier and into the respective adjacent tapering grooves; and holding means on each of the segments and gripping around the respective carrier for projecting into the undercut portion of the respective two adjacent grooves thereby holding the respective segment on the carrier.
 2. Expander as in claim 1, the holding means provided on axial end faces of the segments. 